Crossword puzzles and word search puzzles have been favorite pastimes for millions of people in the United States for generations. These puzzles are available in newspapers and magazines. Custom puzzles are harder to come by. They can be made by hand or with the help of a computer or service. As custom puzzles are becoming easier to make, they are finding more and more use in education and at private parties and other occasions such as weddings, where they are sometimes presented to guests rolled and tied with ribbons.
Crossword puzzles come in several types, including fully-crossed crossword puzzles and freeform crossword puzzles. The main characteristic of freeform crossword puzzles is that they can be made from almost any arbitrary set of answer words. Thus they are the best choice when the puzzle must be on a predetermined topic and generic words are undesirable. It is not necessary to add generic words to make the crossings work. This type of puzzle is often used in education. These puzzles sometimes go by the name criss-cross puzzles.
The main characteristic of fully-crossed crossword puzzles is that all letters in the answer grid are at the intersection of two answer words. This feature has the advantage to the solver that there are always two ways to solve any given cell: the across word and the down word. If the solver finds the clue to an across word too difficult, there are several intersecting down words that when solved can provide additional clues for the difficult across word.
Fully-crossed crossword puzzles often have no theme. If they do have a theme then they typically do not contain many preselected answer words related to that theme. This is because these puzzles require many generic words to make the crossings work.
Sometimes fully-crossed crossword puzzles do have more than just a few words related to a theme. This can be done for topics that are so broad that tens of thousands of words are related to the topic. The topic of television is an example. Another way to provide more entries (clues plus answers) related to the theme is to write a clue for a generic word in such a way as to make it relate to the topic in some way. For example, if the topic is “animals,” words such as “zebra,” “bird,” and “opossum” are inherently part of the topic. Generic words such as “water” and “soft” can be clued in a way that makes them relate to the topic by referring to what most animals drink or the texture of a mink's fur, respectively.
A tightly-crossed crossword puzzle is a crossword puzzle with a grid that would be fully-crossed if it were not for a few blind cells. Blind cells are cells that are in one word only. They are called “blind” because the puzzle solver can not verify the correctness of a guess by turning to a perpendicularly intersecting word. A tightly-crossed crossword puzzle has the same characteristics as a fully-crossed crossword puzzle in the areas where every cell is at an intersection of words and where the words contain no blind cells.
Fully-crossed crossword puzzles are usually made with grids that are symmetrical, meaning that the pattern of black and white squares is identical when it is turned upside down. This is because symmetrical grids are more attractive. Sometimes the term symmetrical crossword puzzle is used loosely to include fully-crossed or tightly-crossed puzzles with grids that have no symmetry.
The main characteristic of word search puzzles is that a predetermined list of words is hidden in a two dimensional array of letters. Usually the hidden words can go in any direction forward, backward, up, down or any of four diagonals. The puzzle can be simplified for children by omitting some of the harder directions. Word search puzzles also go under a variety of names including word find puzzles and circle-a-word puzzles.
Software programs that create freeform crossword puzzles and word search puzzles have been available for decades. Such programs have been available for the Microsoft DOS and Windows and various Apple Computer Inc platforms, as well as other brands of computers. With the advent of the Internet, web sites have sprung up that allow anyone to make freeform crossword and word search puzzles online.
Software and web sites that create word search puzzles and freeform crossword puzzles are not difficult to develop. On the other hand, software that creates symmetrical crossword puzzles has been the subject of many research papers, a few graduate level theses or dissertations and one patent, U.S. Pat. No. 5,667,438.
To create a word search puzzle, these programs and websites provide a way for the user to type in a set of words and press a button to create the puzzle. To create a freeform crossword puzzle, these programs and websites provide a way for the user to type in a set of words and corresponding clues and press a button to create the puzzle. Then they typically show the puzzle and report whether or not all words were used in the puzzle.
This latter report is important because sometimes the program can not get all of the words into the puzzle. One common reason is that the words can not fit inside predetermined maximum dimensions of the puzzle grid. (This limitation may be programmer-imposed or user-imposed.) Typically, this space limitation is the only reason for not getting a word into a word search puzzle. However, for a freeform crossword puzzle, the matter is much more complex:
The answer words can not fit into predetermined maximum grid size.
If the answer words have too many very short words (e.g., 2, 3 and 4-letter words) then these programs can't assemble them into a freeform puzzle. When the words are very short, they have few places on them where another word can intersect. Freeform puzzles work best with a mixture of short and long words.
The answer words include a one-letter word. A one letter word is not long enough to “cross” another word and have some cells extending in a perpendicular direction to show that there is a crossing. Therefore, these programs don't know what to do with one-letter words.
Sometimes an answer word can't hook into the puzzle because it doesn't share any letter with any of the other answer words. For example, for the word CUP to be used in a puzzle, there must be a C, U or P somewhere else among the answer words.
A situation like the latter one can arise, but more complex, in which too many words are trying to hook into the same few letters in the rest of the puzzle. While there may be another C, U or P, it is always tied up by another word either at that letter or immediately next to it.
Even with these challenges, the fact is that most combinations of answer words that people really use can be constructed into a crossword puzzle. Nevertheless, the risk that an important word may be omitted is an annoyance to the user.
When a word is omitted, it is unclear why. The user has to either accept the incomplete puzzle or go back and try again. Trying again may mean just reconstructing over and over with the same word list, hoping that some different set of random events will result in a complete puzzle. If this doesn't work, the user is left to make changes to the answer word list until the software either includes the word or the user gives up trying. Often these changes are meaningless blind guesses formed to overcome a technical problem and are rarely helpful for preparing a better puzzle.
The software program and websites vary in how user-friendly they are, but they do require considerable creativity in coming up with words to find or answer words and clues.